If $$a = \left(\frac{3}{7}\right)^2 \div \left(\frac{9}{7}\right)^0$$​ , then find the value of $$a^{-2}$$​.

Correct option is A

Given: 

$$a = \left(\frac{3}{7}\right)^2 \div \left(\frac{9}{7}\right)^0$$ 

Concept Used:​

​$$a^0 = 1 \\ \ \\ a^{-1} = \frac{1}{a^{-1}}$$​​

Solution: 

$$a = \left(\frac{3}{7}\right)^2 \div 1 = \left(\frac{3}{7}\right)^2$$ 

a = $$\frac9{49}$$ 

Then, 

a^-2= $$\left({\frac9{49}}\right)^{-2}$$​​

​a^-2=  $$\left({\frac{49}{9}}\right)^{2}$$​​

a^-2​= $$\frac{2401}{81}$$​​